Download Health effects of cannabis

Health effects
of cannabis
There are both potential therapeutic uses for and potential
health risks of using cannabis (marijuana). A chemical called
delta-9-tetrahydrocannabinol (THC) is responsible for the way
your brain and body respond to cannabis. While it is used by
some for therapeutic purposes, there are short- and long-term
physical and mental health effects that can be harmful.
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disturbances in mood
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psychotic symptoms
There is also evidence to suggest that combining tobacco
with cannabis can increase:
Short-term health effects
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the strength of some psychoactive effects2
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the risk of poor mental health outcomes, 3
including dependence
While cannabis may make you feel relaxed and happy,
you could experience unpleasant, unwanted or negative
effects on your brain and body.
Effects can be felt within seconds to minutes of smoking,
vaporizing or dabbing cannabis. These effects can last up
to 6 hours or longer.
Effects on the brain
If you eat or drink cannabis, these effects can occur within
30 minutes to 2 hours and can last up to 12 hours or longer.
The short-term effects of cannabis on the brain can include:
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confusion
Effects on the body
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sleepiness (fatigue)
The short-term effects of cannabis on the body can include:
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impaired ability to:
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damaged blood vessels caused by the smoke4
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remember
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concentrate
decreased blood pressure, which can cause people
to faint or pass out
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pay attention
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increased heart rate, which can be a danger for people
with heart conditions and can lead to an increased risk
of heart attack5
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anxiety, fear or panic
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reduced ability to react quickly
Cannabis use can also result in psychotic episodes
characterized by:
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paranoia
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delusions
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hallucinations
Emerging evidence suggests that a chemical in cannabis
called cannabidiol (CBD) may help dampen some of the
psychoactive effects of THC1 such as:
1
Bhattacharyya et al. (2010) Opposite effects of delta-9tetrahydrocannabinol and cannabidiol on human brain function
and psychopathology. Neuropsychopharmacology 35(3): 764–74.
www.ncbi.nlm.nih.gov/pubmed/23550724
2
Ramo et al. (2015) Tobacco and marijuana use among adolescents and
young adults: a systematic review of their co-use. Clinical Psychology
Review 32: 105–121. www.ncbi.nlm.nih.gov/pubmed/22245559
3
Schauer et al. (2017) Marijuana and tobacco co-administration in blunts,
spliffs, and mulled cigarettes: a systematic literature review. Addictive
behaviors. 64: 2011–211. www.ncbi.nlm.nih.gov/pubmed/27654966
4
Wang et al. (2016) One minute of marijuana secondhand smoke
exposure substantially impairs vascular endothelial function.
Journal of the American Heart Association. 5(8).
www.ncbi.nlm.nih.gov/pubmed/?term=27464788
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Thomas et al. (2014) Adverse cardiovascular, cerebrovascular, and
peripheral vascular effects of marijuana inhalation: what cardiologists
need to know. American Journal of Cardiology 113(1): 187–90.
www.ncbi.nlm.nih.gov/pubmed/24176069
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HEALTH EFFECTS OF CANNABIS
Impairment
Effects on the brain
The THC in cannabis can impair your ability to drive safely
and operate equipment. It can also increase the risk of falls
and other accidents. This is because THC can affect your:
The long-term effects of cannabis on the brain can include
an increased risk of addiction and harm to your:
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memory
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coordination
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concentration
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reaction time
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intelligence (IQ)9
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ability to pay attention
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ability to think and make decisions
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decision-making abilities
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ability to judge distances
Cannabis use can increase the risk of accidents that lead to
injury or death during higher-speed activities, such as driving,
biking or skiing.
Impairment can last for more than 24 hours after cannabis
use,6 well after other effects have faded.
People who use cannabis regularly may have trouble with
certain skills needed to drive safely7 for weeks after their
last use.
These effects appear to be worse for youth who start
using early, and who use cannabis frequently and over a
long period of time. They may not be fully reversible when
cannabis use stops.
Effects on the body
Some of the long-term effects of smoking cannabis on
the body are similar to the effects of smoking tobacco
and can include risks to lung health, including:
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bronchitis
Combining alcohol with cannabis greatly increases the level
of impairment and the risk of injury or death from accidents.
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lung infections
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chronic (long-term) cough
Combining cannabis with other psychoactive substances,
especially ones that have sedative effects, such as opioids
and benzodiazepines, can increase the effects of the drugs.
This could increase the risk of injury or harm, particularly
with activities like driving.
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increased mucus buildup in the throat
Long-term effects
Long-term effects develop gradually over time with frequent
use (daily or near-daily) that continues over weeks, months
or years. These effects can last from several days to months
or longer8 after you stop using cannabis.
Potential therapeutic uses
There is some evidence of potential therapeutic uses of
cannabis or its component chemicals (cannabinoids).
Health Canada provides information for health care
professionals and for authorized patients on the use of
cannabis and cannabinoids for medical purposes. This includes
information on dosing, adverse effects, warnings and more.
Risks of illegal cannabis
There may be other health and safety risks associated with
cannabis obtained illegally. For example, the THC potency of
illegal cannabis is often unknown, so you could end up using a
stronger product than expected. This could heighten or prolong
effects such as confusion or anxiety.
The quality and purity of illegal cannabis cannot be guaranteed
and is frequently mixed with or contains:
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8,9
Leirer, V. O. et al. (1991) Marijuana carry-over effects on aircraft
pilot performance. Aviat. Space Environ. Med. 62, 221–227.
www.ncbi.nlm.nih.gov/pubmed/1849400
Karschner et al. (2016) Extended plasma cannabinoid excretion
in chronic frequent cannabis smokers during sustained abstinence
and correlation with psychomotor performance. Drug Testing and
Analysis 8(7): 682–9. www.ncbi.nlm.nih.gov/pubmed/26097154
Meier et al. (2012) Persistent cannabis users show neuropsychological
decline from childhood to midlife. Proceedings of the National
Academy of Sciences USA 109(40): E2657–64.
www.ncbi.nlm.nih.gov/pubmed/22927402
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pesticides
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other drugs
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heavy metals
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moulds or fungi
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other contaminants
HEALTH EFFECTS OF CANNABIS
There is also the serious risk of:
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interacting with criminals or criminal organizations
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criminal charge and prosecution
Health effects on pregnancy
and children
Mental health effects
Just like with tobacco, a pregnant woman or new mother’s
use of cannabis can affect her fetus or newborn child
which can lead to health problems.
In some people, cannabis use increases the risk of developing
mental illnesses like psychosis or schizophrenia, especially
in those who:
The toxins in cannabis are carried through the mother’s
blood to her fetus during pregnancy and in the breast milk
following birth.
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start using cannabis at a young age
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use cannabis frequently (daily or almost every day)
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have a personal or family history of psychosis
and/or schizophrenia
Heavy cannabis use during pregnancy can lead to lower
birth weight of the baby. It has also been associated
with longer-term developmental effects in children
and adolescents, such as:
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Frequent cannabis use has also been associated with
an increased risk of:
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suicide
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depression
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anxiety disorders
Health effects on youth
Cannabis use that begins early in adolescence, that is
frequent and that continues over time has been associated
with increased risk of harms. Some of those harms may
not be fully reversible.10
Adolescence is a critical time for brain development,
as research shows the brain is not fully developed until
around age 25.
Youth are especially vulnerable to the effects of cannabis
on brain development and function. This is because THC
in cannabis affects the same biological system in the
brain that directs brain development.
It is important for parents, teachers, coaches and other
trusted adults to be ready to talk with youth about drugs.
10
Volkow et al. (2016) Effects of cannabis use on human behavior,
including cognition, motivation and psychosis: a review. JAMA Psychiatry
73(3): 292–7. www.ncbi.nlm.nih.gov/pubmed/26842658
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decreases in:
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memory function
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the ability to pay attention
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reasoning and problem-solving skills
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hyperactive behaviour
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increased risk for future substance use
Addiction
Contrary to popular belief, people can become addicted to
cannabis. Individuals who use cannabis can develop a cannabis
use disorder, which at its extreme can result in addiction.
Continued, frequent and heavy cannabis use can cause
physical dependency and addiction.
Research has shown that THC in cannabis causes an increase
in levels of dopamine, the pleasure chemical, in the brain.
This motivates people to keep using it.
Addiction can develop at any age but youth are especially
vulnerable11 as their brains are still developing.
Some people are also more prone to becoming addicted
than others. It’s estimated that 1 in 11 (9%) cannabis users
will develop an addiction12 to it. This statistic rises to about 1
in 6 (17%) for people who started using cannabis as a teenager.
If a person smokes cannabis daily, the risk of addiction is
25% to 50%.
11
Chadwick et al. (2013) Cannabis use during adolescent development:
susceptibility to psychiatric illness. Frontiers in Psychiatry. 4: 129.
www.ncbi.nlm.nih.gov/pubmed/24133461
12
Volkow et al. (2014) Adverse health effects of marijuana use.
New England Journal of Medicine 370(23): 2219–27.
www.ncbi.nlm.nih.gov/pubmed/24897085
© Her Majesty the Queen in Right of Canada, as represented by the Minister of Health, 2017
Cat.: H129-73/2017E (Print) • H129-73/2017E-PDF | ISBN: 978-0-660-08291-2 (Print) • 978-0-660-08290-5 (PDF) | Pub.: 170012
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HEALTH EFFECTS OF CANNABIS
Problematic cannabis use can include some or all of the
following behaviours:
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failing to fulfill major duties at work, school or home
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giving up important social, occupational or recreational
activities because of cannabis use
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consuming it often and in larger amounts or over a longer
period than they intended
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being unable to cut down on or control cannabis use
People who display most or all of these behaviours over a
12-month period may have cannabis addiction.
Some people can develop a tolerance to the effects of
cannabis. Tolerance is characterized by a need for a larger
dose of a drug to maintain the original effects. Tolerance to
some of the effects of cannabis can develop after a few doses.
In some people, tolerance can eventually lead to physical
dependence and/or addiction.
Addiction help
Cannabis addiction can cause serious harm to your health,
social life, school, work and financial future.
If you or someone you know is struggling with addiction
to cannabis or other drugs, help is available.